He was hiding the fact that he was an illegitimate child.

This mineral is called anhydrite.

Maintaining oral hygiene is very important for overall health.

He is working at the pithead.

We steered the ship towards the harbor entrance.

He practices every day to improve his sailing skills.

We plan to sail on a yacht during the summer vacation.

Studying the history of the Imperial Examination is important for understanding the past of our country.

Sexual intercourse is one of the basic human desires.

They were having sex in secret.